Phonograph turntable drive



Nov. 29, 1949 F. L. LINDSTROM 2,489,792

PHONOGRAPH TURNTABLE DRIVE Filed Sept. 13, 1946 2 Sheets-Sheet 1 44 I I l I 4 i I I 3 4 l I I Y INVENTOR. 9- E IRAuKL.LmmsTRnM Nov. 29, 1949 F. L. LINDSTROM PHONOGRAPH TURNTABLE DRIVE 2 Sheets-Sheet 2 Filed Sept. 15, 194B uvvzvmt I RANK L.Lm11sflznM ATTORNEY Patented Nov. 29, 1949 UNITED STATES FATENT OFFICE PHONOGRAPH TURNTABLE DRIVE Frank L. Lindstrom, Bridgeport, Conn.

Application September 13, 1946, Serial No. 696,767

1 Claim.

This invention relates to new and useful improvements in drives for turntables of phonographs and has particular relation to a simple and inexpensive construction for the driving of a phonograph turntable by frictional engagement with the usual inturned flange thereof.

The objects and advantages of the invention will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawings wherein a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the spirit of the invention and the scope of the appended claim.

In the drawings:

Fig. 1 is a top plan view of the improved turntable drive, a portion only of the turntable being shown;

Fig. 2 is a top plan view of the supporting plate and mounting plate detached from the other mechanism, the position of a friction pulley being indicated by broken lines and the parts being positioned as when disassociated from a turntable;

Fig. 3 is a view similar to Fig. 2 but with the mounting plate in its extreme inner position;

Fig. 4 is a sectional view taken as along the line 4-4 of Fig. 1, the motor being shown in elevation;

Fig. 5 is a top plan view of the supporting plate with but a small portion of the mounting plate thereover;

Fig. 6 is an edge view of the parts shown in Fi 5;

Fig. '7 is a top plan view of the mounting plate alone; and

Fig. 8 is an edge view thereof.

Referring in detail to the drawings, at I0 is shown a base plate having a relatively large hole ll therethrough. This base plate is adapted to be mounted on the deck or platform of a phonograph cabinet as is usual in the art. Disposed at the upper side of the plate l0 and spanning the opening H, is a supporting plate l2 shown as having three legs or extensions l3 extending beyond the hole I I and separated from the base plate as by rubber or other cushioning gaskets l4.

Bolts i5 pass through the base 10 and tapped openings in the lugs or legs l3 and serve to secure the supporting plate to the base. Preferably, vibration absorbing pads [6 are interposed between the bolt heads and the base and metal washers [1 may be disposed between the bolt heads and the said pads. The pad 16 as well as the gaskets 14 are of a sound absorbing material.

The supporting plate 12 is further provided with a pair of holes l8 for the passage of screws or other means used for mounting a motor 19 .1

at the underside of said plate. As here shown, the motor is secured to the plate and in spaced relation therewith through the medium of a pair of posts 29 and bolts 21 which latter may pass through the openings 18.

Additionally, a flange-like lug 22 is lanced and pressed from the body of the supporting plate 12 and such lug is in fixed relation to a pair of openings 23 and 24. Opening 23 is of a diameter to provide for the free passage of the shaft 25 of the motor and such shaft at the upper side of the plate 12 carries a friction pulley 26. The purpose of opening 24 will appear.

Disposed on the upper side of the plate I2 is a mounting plate 21 considerably smaller than the plate i2. A series of nipple-like projections 28 are pressed to extend to the lower side of the plate 21 and in the complete assembly rest on the upper side of the plate 12 and provide for the spacing of the plates and for the ready sliding movement of plate 21 on the plate 12,

Plate 21 is provided with a relatively large diameter opening 29, the purpose of which will appear, and it is provided with a further opening in which is mounted a bearing 30. As shown, the main body of plate 21 is provided with a pair of leg-like lateral extensions 3| and 32 of which the former has a rounded outer end 33 while the latter carries an upwardly bent perforated lug 34.

A rivet 35 has its shank portion 36 passing through a relatively large opening 29 in the mounting plate. Such shank portion is of two diameters and its portion remote from its head is of the smaller diameter and is passed through the supporting plate 12 and headed over as at 31. In this way the rivet is made fast to the supporting plate and has its head 38 in predetermined spaced relation to the latter. The rivet head 33 is of a diameter in excess of that of the opening 29 whereby when the rivet is in place the mounting plate 21 is held against any appreciable movement away from the supporting plate but is slidably movable relative thereto within the limits permitted by the diameter of the hole 29 relative to the diameter of the rivet shank portion of larger diameter.

In the assembly, the rounded portion or end 33 of the lateral leg-like extension 3! of the mounting plate is constantly against or in the immediate vicinity of the flange-like ing 22. Further, in the assembly, the lower end portion of the bearing 30 is accommodated in the relatively large diameter opening 24 and the relative sizes of the opening and the bearing is such as to permit movement of the mounting plate on the supporting plate within the limits allowed and by the relative size of the opening 29 and that portion of the rivet shank of larger diameter.

' The bearing 30 receives a shaft 39 at its upper end carrying an idler wheel 40 having a friction annular flange s5.

pulley 26 on the motor shaft.

tire 4| about its peripheral edge. Anchored at its inner end to the lug 34 of the mounting plate and at its outer end to a similar perforated lug 42 on the supporting plate is a coil spring 43. This spring is constantly tending to move or slide the mounting plate 2? so as to carry the frictional tire 48 of the idler wheel as into engagement with the friction pulley on the motor shaft.

Fig. 2 suggests the relative positions of the parts when there is no turntable :in' place and there it will be noted the end 33 of leg-like extension 3| is against the flange-like lug'22. The bearing is to one side of the center of the opening 2/3 and the opening 29 of the mounting plate has one edge against the shank 36 of the rivet 35.

In Fig. 3 the parts are in their other extreme position and it is noted that the location of the hole 29 relative to the rivet shank and the location of the bearing 39 in the hole Z lof the supporting plate is each opposite the locations as shown in Fig. 2. This shows the mounting plate in its extreme inward position.

In Fig. 1, the actual operating relationship of the parts is shown and in such figure a fragment 44 for a turntable is shown and such turntable, as usual, is provided with an inturned In this figure, the friction tire 4| of the idler wheel is against the inner surface of the flange 45 and is also against the Also, the rivet shank as is approximately centered in the hole 29 of the mounting plate and the bearing 38 carried by the latter is approximately centered in the opening 24 of the supporting plate.

Obviously, in Fig. 1, the spring 43 is tending to pull the idler wheel about the pulley 26 in a direction to maintain the tire of the idler wheel not only against the pulley but also against the inner surface of the flange 45 of the turntable. Therefore, when the motor is in operation it will, through the pulley 2%, drive the idler wheel and the latter through its frictional engagement with the flange 45 will rotate the turntable. As suggested, the turntable is mounted on any suitable shaft 46 for rotary movement and the table includes a hub portion 41 receiving the shaft.

From the above description it will be seen that I have provided an extremely simple construction for accomplishing the desired objective. The plate i2 is easily blanked and formed, as is the plate 2'5. The rivet holds the plates against movement away from one another and it, together with the sliding or fulcrum contact between the rounded edge portion 33 of the mounting plate and the flange-like lug 22 of the supporting plate, provides the necessary guides for movement of the mounting plate on the supporting plate.

A comparison of Figs. 1, 2 and 3 shows that in any of the various positions of the mounting plate on the supporting plate the friction tire H of the idler wheel is maintained in contact with the friction pulley 25 on the motor shaft. The spring 43 accomplishes this. With the tire bearing on the pulley the tendency of the spring 43 is to shift the mounting plate around such pulley and this results in a rocking of the plate 21 and also a shifting of the plate outwardly or toward an edge of the supporting plate so as to carry the idler wheel outwardly of the latter. Thus in Fig. 2 the idler wheel projects to such an extent that its tire would be under or slightly beyond the flange of the turntable.

Thereafter, when a turntable is being positioned, the idler wheel is manually pushed inwardly to position its tire at the inner side of the turntable flange as in Fig. 1. Fig. 3 shows the idler wheel in its innermost position such as to the position it might be manually pushed in order to position the turntable. After the turntable is positioned, the idler wheel is released from the position of Fig. 3 and the spring shifts it outwardly to the position of Fig. 1.

With the present construction, the mounting plate is provided with but two openings and one of these receives the bearing 36. In addition to its engagement with the surface of the supportingplate, the mounting plate has a rounded edge 33 to engage the upstanding flange-like lug 22 of the supporting plate. The supporting plate itself is'provided with but two openings 23 and 2% for theaccommodation of the motor shaft and the bearing 36. The only means for fastening or interlocking the supporting and mounting plates is the single rivet 35. From the above it will be seen that I have provided a simple and inexpensive construction for my present purpose and yet a construction providing for a long, useful life.

Having thus set forth thenature of my invention, what I claim is:

In a phonograph turntable drive, a metal supporting plate, a motor mounted on said plate and located at the underside thereof, a rotatably -mounted turntable extending over the upper side of said plate and having a downturned annular flange, said motor including a shaft extending freely through an opening in said supporting plate and at the upper side of the latter mounting a friction pulley, a small mounting plate on the upper side of said supporting plate and slidably movable thereon, a stud rigid with said supporting plate and extending freely through a hole in the mounting plate and at the upper side of the latter rigid with a head of larger diameter than said hole, a flange-like lug extending upwardly at right angles from the upper side of said supporting plate and having a flat surface normal thereto, a lateral extension on an edge of said mounting plate, said extension having a convexly curved edge surface engageable with said surface of said lug through lateral bodily movement of said mounting plate toward said surface of the lug and dis-engageable therefrom through lateral movement away from said lug, said surface of said lug also slidably engageable by said convexly curved edge of said extension on bodily movement of said mounting plate in a direction parallel with the plane of said surface of the lug, an idler wheel rotatably mounted on a portion of said mounting plate diagonally opposite said extension and at the opposite side of the stud receiving opening therefrom, said idl r wheel having a friction tire for contact with said friction pulley and said annular flange, and spring means associated with said mounting plate and urging the latter in a direction to maintain the idler wheel in contact with said friction pulley and said downturned annular flange.

FRANK L. LINDSTROM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,161,148 Erwood June 6, 1939 2,261,889 Schneider Nov. 4, 1941 I 2,455,280 Sweighert Nov. 30, 1948 

